EP2660794B1 - Method and device for identifying a vehicle using a space - Google Patents

Description

The present invention relates to a method for identifying a vehicle using a given location. The invention further relates to a radio beacon and an onboard unit for use in this method.

Vehicle identification methods are needed, for example, for recording, checking, authorizing and / or tolling (billing) of local uses of vehicles. Such local uses can be, for example, entry into restricted or supervised areas, a paid stay at a certain place, such as a paid parking, or the use of toll roads such as highways or inner cities (city toll), etc. In known methods for vehicle identification either vehicle license plates (number plates) are read by means of OCR (optical character recognition), or the vehicles are as in the EP 1 519 320 A1 proposed equipped with on-board units (OBUs), which have a unique identification, which via a radio interface such as DSRC (dedicated short range communication), RFID (radio frequency identification), WLAN (wireless local area network), WAVE (wireless access for vehicular environments). can be read out.

In order to create a concrete assignment of a radio-read OBU identification to the place used by the vehicle, the radio beacons used for radio reading are currently being set up on special bridges ("gantries") to the location to be monitored and equipped with narrow radio coverage areas; or satellite navigation-based onboard units are used, which send their self-determined position data via a mobile radio network to a central office, which performs a map matching with locations to be monitored. All these known methods require not only special, complex installations both in the vehicle and also on the road, but also reveal the identity of the OBU (in the form of the radio-read OBU identification), even if there is no location to be monitored, which is questionable for data protection reasons.

The invention has for its object to provide methods and apparatus of the aforementioned type, which allows the identification of location-using vehicles in a simpler manner and with improved confidentiality for uninvolved vehicles.

• auf dem Fahrzeug Mitführen einer Onboard-Unit, die wiederholt Statusmeldungen über Funk aussendet, welche jeweils einen aktuellen Relativabstand der Onboard-Unit zu dem vorgegebenen Ort und eine nach jeweils einer oder mehreren Statusmeldungen wechselnde Funkkennung angeben,
• Empfangen zumindest einer Statusmeldung in einer Funkbake,
• Detektieren einer Ortsnutzung des Fahrzeugs durch Auswerten der zumindest einen Statusmeldung anhand des darin angegebenen Relativabstands,
• Senden einer Identifikationsanfrage von der Funkbake an die durch die Funkkennung aus der zumindest einen Statusmeldung adressierte Onboard-Unit,
• Empfangen und Berechtigungsprüfen der Identifikationsanfrage in der Onboard-Unit und, wenn die Anfrage berechtigt ist, Senden einer über mehrere Funkkennungswechsel gleichbleibenden eindeutigen Identifikation der Onboard-Unit an die Funkbake.

This object is achieved in a first aspect of the invention with a method of the type mentioned above, comprising:

• on the vehicle carrying an on-board unit which repeatedly emits status messages via radio, each of which indicates a current relative distance of the onboard unit to the given location and a radio code changing according to one or more status messages,
• Receiving at least one status message in a radio beacon,
• Detecting a location utilization of the vehicle by evaluating the at least one status message based on the relative distance specified therein,
• Sending an identification request from the radio beacon to the onboard unit addressed by the radio identifier from the at least one status message,
• Receiving and authorization checking of the identification request in the onboard unit and, if the request is justified, sending a unique identification of the onboard unit to the radio beacon which remains the same over a plurality of radio ID changes.

The invention is based on a novel integration of status messages transmitting onboard units, as for example in the standards ITS-G5 or WAVE (IEEE 802.11p) in the form of, for example, CAM messages (common awareness messages) or BSM messages (basic safety messages ) are defined. The messages are referred to as broadcasts for warning or information from adjacent on-board units or roadside Infrastructure broadcast to avoid collisions or to provide the driver with improved situation overview. To complicate the creation of movement profiles of a vehicle, the privacy status messages are only sent out under temporary, from time to time changing and unknown to the system operators radio IDs. The invention only evaluates the temporary radio identifications of at least one status message of the on-board units. Only after the location usage - due to the temporary radio IDs - has been detected anonymously - is the on-board unit requested to declare its "true" identity, eg payment, user or application identity. This ensures that actually only those on-board units are identified that have used the given location; On-board units of third-party vehicles that pass by the location only nearby or near the actual location use, etc., are not identified, ie remain anonymous. Thus, high privacy privacy requirements can be met without the need for expensive roadside installations, OBU modifications or separate anonymization facilities such as proxy computers.

By the measure according to the invention that each onboard unit itself calculates its relative distance to the predetermined location and sends the finished calculation result to the radio beacon, this is relieved of the compute-intensive distance calculation. The radio beacon only needs to evaluate the relative distances, e.g. Check for falling below a predetermined maximum distance to detect the local use.

According to a first embodiment of the invention, information about the predetermined location is sent by the radio beacon to the onboard unit and calculates from this and from its current position the relative distance.

Alternatively, information about the given location can be stored in the on-board unit and this calculates the relative distance therefrom and from its current position. For example For example, each on-board unit may contain lists of locations of radio beacons as predefined locations, pre-stored or received by radio, for example distributed by radio beacons, and use these lists to determine the relative distance to the nearest radio beacon.

A further preferred embodiment of the invention is characterized in that at least two status messages are received in a radio beacon and assigned to each other based on the radio IDs specified therein, and that the location usage of the vehicle is detected by evaluating the associated status messages based on the relative distances specified therein.

By assigning and evaluating at least two status messages, an onboard unit is tracked over a short time, which is sufficient to determine the use of a specific location with high security. For this purpose, two or a few status messages which can be assigned to one and the same on-board unit can already be sufficient to rule out measurement errors and to be able to reliably detect a movement taking place with regard to an increasing or decreasing relative distance. In the simplest case, a location usage detected in this way may be the crossing of a predetermined limit around the specified location if the first status message indicates a relative distance outside the boundary and the second status message indicates a relative distance within the boundary in order to detect location usage.

According to a further preferred embodiment of the invention, the authorization check is carried out by checking a sent by the radio beacon with the identification request cryptographic sender certificate of the radio beacon. As a result, the onboard unit reveals its identity to only identified, authorized users, further enhancing privacy protection.

For the same reason, it is particularly advantageous if the identification of the onboard unit via an encrypted channel is sent to the radio beacon. For this purpose, a direct (point-to-point) encrypted communication between onboard unit and requesting radio beacon can be established. The encrypted communication channel may for example be part of the protocol on the radio interface between onboard unit and radio beacon, eg part of the ITS G5 or WAVE standard, but could alternatively also be established separately via a 3G, 4G or 5G mobile network.

In a preferred application of the identification method of the invention, the identification received in the beacon, together with a time stamp, is recorded in a memory to log the location usage, e.g. for surveillance purposes.

In an alternative application of the method of the invention, the identification received in the radio beacon is compared with at least one prestored authorized identification to authorize location usage, for example to open barriers, lower a wheel lock, deactivate an enforcement system, etc.

In a further application of the identification method of the invention, the identification received in the radio beacon is used to locate and debit a toll account assigned to the identification in order to congest the location usage, for example for collecting local and / or time toll, parking fees, road user charges, city toll or the like. like.

In all three variants may be preferably provided that the radio beacon after logging, authorization or Vermautung the use of local sends a unique for the beacon beacon identifier to the onboard unit, which stores them and at least one next sending their status message (s) or sending their Identification sends, and that the radio beacon ignored a status message or identification received from an on-board unit, if the beacon identifier mitepangene is equal to their own beacon identifier. This can result in accidental duplicate logging, authorizations or -Vermausungen one and the same onboard unit in the radio coverage area of a radio beacon prevented.

According to a further preferred feature of the invention, more than two status messages can be received and assigned to one another, and a movement tendency of the onboard unit can be calculated from the relative distances specified therein, which is compared with the predetermined location for the purpose of detecting the location usage. As a result, the detection reliability can be increased and, for example, "measurement outliers" can be better suppressed.

It is particularly favorable if the radio code is changed after about 5 to 1000, preferably 20 to 100, status messages. The more frequently the radio code changes, the greater the data protection with regard to the traceability of a particular on-board unit; the less frequently the radio code changes, the lower the danger that the radio code changes around the location to be detected, which would make the detection more difficult. The above values are a good compromise between these two conflicting requirements.

Alternatively, the change interval of the radio identification of the on-board unit can also be set so that the radio identification is changed at the earliest after expiry of a predetermined period of time. The predetermined period of time may be set based on the size of a conventional radio coverage area of a radio beacon and an average speed of onboard units such that no radio ID change occurs when an onboard unit passes a radio beacon with high certainty.

A further preferred embodiment of the invention consists in that the radio identifier is not changed as long as the onboard unit is located in the radio coverage area of one and the same radio beacon. For this purpose, the onboard unit can measure, for example, the radio coverage area of a radio beacon itself if the radio beacon periodically emits beacon IDs, or on the basis of pre-stored lists or maps of radio coverage areas known radio beacons determine, or from be notified of a radio beacon as part of one of their emissions or their identification request.

The status messages can also contain the current position and / or a current motion vector of the on-board unit, which is / are used to detect the location usage in order to further increase the detection reliability.

According to a further preferred feature of the invention, the current position of the on-board unit can be determined by satellite navigation and improved by reference to a satellite navigation reference position of the radio beacon, in the manner of differential GPS (dGPS), the beacon transmitting the reference receiver Improvement of the satellite navigation-specific positions of the on-board units.

Alternatively, the current position of the onboard unit can be determined by means of satellite navigation and improved by reference to at least one further position determined by satellite navigation of an adjacent onboard unit. This embodiment is based on the assumption that the onboard units located in the radio coverage area of a radio beacon are each subject to the same satellite navigation errors due to their proximity, and therefore neighboring OBUs can be used as comparison receivers in the manner of dGPS.

In principle, a beacon could be used to detect location uses in its narrower or wider neighborhood or even in remote areas outside its radio coverage area; However, the radio coverage area of the radio beacon preferably contains the predefined location, so that each radio beacon is responsible for location uses in its immediate surroundings and thereby obtains on-site units with time and location-related measurement data.

In a second aspect, the invention provides a radio beacon for identifying a vehicle using a given location, which carries an on-board unit that repeatedly emits status messages via radio, each having a current relative distance of the onboard unit to the specified location and indicate a changing after each one or more status messages radio identifier, the radio beacon is designed for using a processor and a connected transceiver
to receive at least one status message,
to detect a location utilization by evaluating the at least one status message on the basis of the relative distance specified therein;
send an identification request to the onboard unit addressable by the radio identifiers from the at least one status message, and then
to receive a unambiguous identification of the onboard unit that remains the same over a plurality of radio ID changes.

It is particularly favorable when the radio beacon is designed for
to receive at least two status messages and to assign them to one another based on the radio identifiers specified therein, and
to detect the location of the vehicle by evaluating the associated status messages based on the relative distances specified therein.

The radio beacon preferably contains a cryptographic sender certificate and is designed to send it along with the identification request.

In a third aspect, the invention provides an on-board unit with a processor, a satellite navigation receiver for position determination and a transceiver for radio communication, wherein the onboard unit is designed to repeatedly send out status messages via radio with the aid of the transceiver, which in each case one after several Status messages contain changing radio ID of the on-board unit,
the on-board unit being further adapted to indicate in its status message its current relative distance to a given location as determined by the satellite navigation reception,
receive an identification request from a radio beacon addressed to its current radio identifier and containing a cryptographic sender certificate;
to validate the sender's certificate and, if it is valid,
to send a unique identification of the on-board unit to the radio beacon which is consistent over several changes in the radio ID.

The status messages of the on-board unit are preferably modified CAM messages according to the ITS-G5 standard or modified BSM messages according to the WAVE standard.

• Fig. 1 im Rahmen des Verfahrens der Erfindung wirkende Komponenten einschließlich der Funkbake und mehrerer Onboard-Units der Erfindung in einem schematischen Überblick;
• Fig. 2 ein Blockschaltbild und gleichzeitig Signalflussdiagramm des Verfahrens der Erfindung; und
• Fig. 3 ein Sequenzdiagramm des Nachrichtenaustauschs auf der Funkschnittstelle zwischen Funkbake und Onboard-Unit.

With regard to further features and advantages of the radio beacon and onboard unit of the invention, reference is made to the above explanations of the method and the following description of preferred embodiments, which is given with reference to the accompanying drawings, in which:

• Fig. 1 acting in the context of the method of the invention components including the radio beacon and several on-board units of the invention in a schematic overview;
• Fig. 2 a block diagram and at the same time signal flow diagram of the method of the invention; and
• Fig. 3 a sequence diagram of the message exchange on the radio interface between the radio beacon and onboard unit.

Fig. 1 "As an exemplary application of the identification method of the invention, there is shown a road toll system 1 having a center 2 and a plurality of associated, geographically distributed roadside entities (RSE) 3. The beacons 3 each have a limited radio coverage area 4, eg a radio radius of 200 m within which predetermined locations such as points 5 ("virtual toll booths"), areas 6 (eg parking lots), boundaries 7 (eg virtual "gantries", inner city boundaries, etc.) or road segments 8 are defined, the locations 5 - 8 may also be wholly or partially outside the radio coverage area 4. Preferably, they are (at least partially) within the radio coverage area 5, which simplifies the assignment of a radio beacon 3 to the locations 5-8 for which it is responsible.

The radio beacons 3 detect location uses of vehicles 9 that pass their radio coverage area 4, i. whether - and optionally how long - they use one of the locations 5-8, and identify such location-using vehicles 9. Vehicles 9 that do not use any of the locations 5-8 are not to be identified, i. remain anonymous.

For the purposes mentioned, all vehicles 9 are equipped with on-board units (OBUs) 10 whose construction is based on Fig. 2 is explained in more detail.

According to Fig. 2 For example, each OBU 10 has a satellite navigation receiver 11 for continuously repeating its position fixes P ₁ , P ₂ , ..., generally P _i , in a global navigation satellite system (GNSS) such as GPS. GLONASS, Galileo, or the like on. Furthermore, the OBU 10 is equipped with a processor 12 and a transceiver 13, with some of the data connections between satellite navigation receiver 11, processor 12 and transceiver 13 not shown for clarity.

14 schematically designates a service application executable by the processor 12, for example a toll application which can interact with the beacons 3 and the center 2 of the road toll system 1 in the manner to be discussed later and for this purpose via a unique OBU identifier uID in the road toll system 1 ("unique ID"). The OBU identification uID can be, for example, a unique production identifier of the OBU 10, the name of its owner, the name of the vehicle owner of the vehicle on which the OBU 10 is mounted, an account or credit card identifier of the vehicle owner or the like. be. The OBU identification uID is known in the road toll system 1 of the control center 2 and / or the radio beacon 3 and can there to identify the vehicle 9, which carries the OBU used.

15 designates a security application processed by the processor 12, by means of which the OBU 10 continuously repeats, preferably periodically approximately every 100 ms, a status message 16 via its transceiver 13. The status message 16 is intended to be received by OBUs 10 of adjacent vehicles 9 and / or roadside infrastructure such as the radio beacons 3, and requires neither acknowledgment of receipt nor actual reception; the application 15 sends status messages 16 via the transceiver 13 regardless of whether or not they are received by a receiver, but optionally may also be prompted by radio beacons 3 or other OBUs 10 to do so.

The status messages 16 may each contain the last of the satellite navigation receiver 11 determined position P _{i of} the OBU 10 and optionally also other data, such as speed and direction of movement (motion vector) M, altitude, measurement accuracy, etc. Each status message 16 is provided with a temporary radio ID pID, so that neighboring OBUs or infrastructure correlate successive status messages 16 based on the temporary radio ID pID, ie, can assign to each other at least for a short time the trajectory of an OBU 10 based on the positions P _i can be determined from successive status messages 16.

Onboard units 10 with security applications 15 for sending such status messages 16 are defined, for example, in the standards ITS-G5 and WAVE (IEEE 802.11p). Status messages 16 of this type are called "common awareness messages" (CAM) in the ITS-G5 standard and "basic safety messages" (BSM) in the WAVE standard (in particular SAE J2735). The temporary radio code pID of a status message 16 can be, for example, a temporary IP6 address, a MAC address or pseudo MAC address of the OBU 10, an exact or preferred generalized geo-position (location coordinates) of the OBU 10, or the like. In the simplest case, therefore, the temporary radio code pID can even be equal to the position P _{i of} the OBU 10.

The radio ID pID is not known in the road toll system 1 or the center 2 and the radio beacon 3 and has no meaning there; It can also be chosen randomly by an OBU 10, for example. The radio ID pID is also "temporary" in the sense that it changes after a certain number of status messages 16 in order to prevent tracking of a specific OBU 10 over a longer period of time. For example, the radio code pID is changed after every fifth to thousandth, preferably every twentieth to one hundredth, status message 16. This method is in the sequence diagram of Fig. 3 shown in more detail.

Alternatively, the radio identity pID may be changed after a predetermined period of time, or the change may be selectively omitted, i. be suppressed by the onboard unit 10, as long as it is in the radio coverage area 4 one and the same radio beacon 3. The on-board unit 10 may have pre-stored information about the position of a radio beacon and / or the size of the radio coverage area 4, e.g. in the form of lists or maps, or even received by a beacon 3, be it in the form of periodic broadcast broadcasts a radio beacon 3 or in the course of the later-discussed messages 22, 27 and 27 '.

For the purposes of the method presented here, the status messages 16 are modified compared to conventional CAM or BSM messages insofar as they - instead of or in addition to the current position P _{i of} the OBU 10 - respectively the current relative distance A _{i of} the OBU 10 a predetermined location 5 - 8 included. For this, it is necessary that the OBU 10 has information about the location coordinates (geo-position) P _{0 of} the predetermined location 5 - 8, for example, the point 5 or the center or a reference point of the area 6, the boundary 7, of the road segment 8 etc.

The position information P _{0 of} the predetermined location 5 - 8 can be pre-stored in the OBU 10, for example as a list, both during production or delivery of the OBU 10 and "stored on the fly", for example, received by one of the radio beacons 3 or from the central office 2 via the network of radio beacons 3 or another radio network, eg a mobile radio network, to the OBUs 10 distributed. If there are a plurality of predefined locations 5-8, the OBU 10 sends the relative distance A _i to the nearest location 5-8, for example in the status messages 16, unless it receives an order from a beacon 3 or in some other way, the relative distance A _i to calculate to other than the nearest place 5 - 8.

wobei (X_i/Y_i/Z_i) die Koordinaten der aktuellen Position P_i der OBU 10 und (X₀/Y₀/Z₀) die Koordinaten der Position P₀ des vorgegebenen Orts 5 - 8 sind. Selbstverständlich kann die Berechnung auch ausschließlich in der zweidimensionalen Ebene X/Y durchgeführt werden, d.h. die Z-Koordinaten können unberücksichtigt gelassen werden.The calculation of the relative distance A _i between the current position P _{i of} the OBU 10 and the position P _{0 of} the predetermined location 5-8 is a classical calculation of the length of the vector from P ₀ to Pi according to the equation $$A_i=\sqrt{{\left(X_i-X_0\right)}^2+{\left(Y_i-Y_0\right)}^2+{\left(Z_i-Z_0\right)}^2}.$$

where (X _i / Y _i / Z _i ) the coordinates of the current position P _{i of} the OBU 10 and (X ₀ / Y ₀ / Z ₀ ) are the coordinates of the position P _{0 of} the predetermined location 5-8. Of course, the calculation can also be carried out exclusively in the two-dimensional plane X / Y, ie the Z coordinates can be left unconsidered.

According to Fig. 3 the OBU 10 repeatedly sends status messages 16, herein designated CAM ₁ , CAM ₂ , CAM ₃ ..., generally CAM _i . In the example shown, the radio code pID _n changes after the first three status messages 16 or CAM ₁ , CAM ₂ , CAM ₃ from pID ₁ to pID ₂ , etc., etc. In the ith status message CAM _i , the n-th radio code pID _n used (n << i).

With statistically high probability, therefore, two consecutive status messages 16 can be assigned to each other on the basis of their same radio ID pID _i ; only at Radio ID change pID _n on pID _{n + 1} , a direct correlation of the status message 16 before and after the radio ID change is not possible. In this case, a correlation of the status messages 16 can also be carried out by tracking the movement history ("tracking") of the on-board unit 10, for example by evaluating its speed, direction vector, etc., be it in the status messages 16 from the OBU 10 be communicated or measured by the radio beacon 3. Also, characteristics of the vehicle 9 carrying the OBU 10, such as vehicle width, length, altitude, etc., could be stored in the OBU 10 and communicated in its status messages 16 or measured by the beacon 3 to increase correlation confidence.

According to the Fig. 1-3 is thus a radio beacon 3, which receives the status messages 16 all passing in their radio coverage area 4 OBUs 10, capable of the outgoing from a particular OBU 10 status messages 16 based on the radio IDs pID each other and thus the tendency of the OBU 10 from the relative distances A _i , optionally the entire trajectory of the OBU 10 from the positions P _i , if they are mitbegmittelt follow. For this purpose, the radio beacon 3 according to Fig. 2 via a processor 17, a transceiver 18 and a processing process 19 processed by the processor 17, which filters the stream of incoming status messages 16 with respect to correlating radio IDs pID and supplies the relative distances A _i from the associated status messages 16 to a tracking process 20 processed by the processor 18 , If the radio identifications pID correspond directly to the positions P _i or to generalized geopositions resulting therefrom, the assignment process 19 can also carry out the mutual assignment of the status messages 16 on the basis of a movement history (tracking) of the OBU 10.

The tracking process 20 compares the resulting relative distances A _i with a maximum distance a _m from a predetermined location 5-8 to detect a location usage. Also can the tendency of the OBU 10 to be monitored progressively or progressively decreasing relative distances A _{i in} order to detect or suppress measurement outliers and to reliably detect the exceeding of the distance limit a _m .

In addition, the current positions P _i , if they are also transmitted, can be evaluated in order to further increase the detection reliability. Since the distance calculation according to equation 1 takes place in the OBU 10, the tracking process 20 in the radio beacon 3 can be kept very simple and can be based, for example, on the simple comparison "A _i <a _m ?" to reduce. Optionally, however, a plurality of relative distances A _i sent in successive status messages 16 can also be evaluated jointly, for example their mean value can be formed and compared with the maximum distance a _m .

If the predetermined location P _{0 is} a point 5, the spatial use detected on the basis of the relative distances A _i can additionally be validated if a predetermined number or an average of positions P _i falls below a maximum distance a _m from point 5. If the location is an area 6, the location usage detection may be additionally validated if a predetermined number or average of positions P _i falls within the area 6. If the location is a road segment 8, the location usage detection may be additionally validated if, for example, the positions P _i indicate full drive of the road segment 8 from its beginning to its end, or driving a predetermined sequence of several consecutive road segments 8 or the like If the location is a boundary 7 (which, incidentally, can also be used to limit the circumference around the point 5, the area 6 or the road segment 8), then the detection of the location usage can be validated in addition to detecting an exceeding of the boundary.

In a simplified embodiment, the radio beacon 3 can already from a single status message 16 a local use detect, so that the assignment process 19 can be omitted. In this case, for example, a location usage can be detected if a single relative distance A _i falls below the maximum distance a _m around the point 5. If the status message 16 contains additional data such as speed and direction of movement, in particular a motion vector M, the OBU 10, location usage may also be detected if extrapolation results in the past or future movement of the OBU 10 just before, just or has used, used or will soon use a location, eg the maximum distance a _m below or the limit 7 has exceeded or will exceed.

As soon as the tracking process 20 detects a location usage, it starts a service application 21 responsible for this location usage, which is processed by the processor 17. The application 21 may e.g. a logging, control or authorization service to record or monitor the detected location usage - identified for the OBU 10 - or to authorize further steps such as opening an access barrier or the like. In the present example, the service application 21 is a leased service with the service identification sID, which can charge (charge) the location usage for the OBU 10.

The service application 21 now sends an identification request Id_Req 22, optionally together with its service identification sID, via the transceiver 18 to the OBU 10 with that radio identifier pID that was specified in the status messages 16 assigned by the assignment process 19, see also Fig. 3 , The identification request 22 preferably contains a cryptographic sender certificate "Cert" 23 of the radio beacon 3 in order to authenticate it to the on-board unit 10.

The OBU 10 addressed by the radio identifier pID receives the identification request 22 and forwards it to the corresponding process, here the toll application 14. If the identification request 22 contains a sender certificate 23, can the OBU 10 in an optional step 24 ( Fig. 3 ) check the authenticity of the certificate 23; if this is valid then it will carry out the further steps; otherwise, the identification request 22 is ignored.

The OBU 10 answers the identification request 22 by releasing (disclosure) its system-wide unique, i. Also over several changes of the radio ID pID consistently unique identification uID, see declaration message Id_Rsp 25, which sends them back via the transceiver 13 to the transceiver 18 of the radio beacon 3. The declaration message 25 may contain the service identifier sID of the querying service application 21 of the radio beacon 3, so that the declaration message can there be supplied to the correct service application 21.

The OBU 10 is now identified with its unique identifier uID against the service application 21, and the latter with its service identifier sID and its certificate 23 to the OBU 10 and the toll application 14. Via the radio interface 26 between the transceiver 13 of the OBU 10 and transceiver 18th the radio beacon 3 can therefore be exchanged now more service-specific messages Svc_Msg 27. The messages 27 may, for example, be data packets of a conventional toll protocol for tolling the location usage. For example, the OBU identification uID can refer to a toll account in the radio beacon 3 or the central station 2, which is charged with tolls for the location use. Alternatively, the identification uID could be compared with (at least) one authorized (reference) identification uID _ref pre-stored in the radio beacon 3 or the center 2, wherein the equality case authorizes the identification uID eg for a local access or for the receipt of a service.

As soon as the radio beacon 3 and the OBU 10 are mutually authenticated, in particular by evaluating the sender certificate 23 of the radio beacon 3, all subsequent communications, such as the declaration message 25 and the subsequent service messages 27, can be encrypted via the radio interface 26 are transmitted, for example as an encrypted point-to-point communication. Such an encrypted transmission channel could alternatively be established via the radio interface 26 via a (not shown) mobile telephone network, for example, directly to the control center. 2

In a simplified embodiment, in which the radio beacon 3 does not perform a tolling function, but merely serves to identify the vehicles 9 or OBUs 10, the identifications uID of the on-board units 10-preferably in each case together with a current time stamp t-can simply be just as well for logging purposes in a memory 28 of the radio beacon 3 or central 2 are recorded.

In an optional step 27 ', the radio beacon 3 after a successful logging, authorization or Vermautung a location use an acknowledgment message "ok" to send the OBU 10, in which it (possibly again) sends a unique beacon identifier bID. The OBU 10 may store beacon IDs bID received from radio beacons 3 and send at least each beacon identifier bID last received in one (or more) of its status messages 16 and / or upon disclosure of its identifier uID in step 25 to a beacon 3. The beacon 3 can thereby ignore or hide those status messages 16 and / or identification broadcasts 25 with which it also receives a beacon identifier bID that is equal to its own beacon identifier bID in order to avoid duplication of one and the same passing OBU 10.

In determining the current positions Pi and the relative distances A _i , the positions P _{i of} an OBU 10 can be improved by comparison with known reference positions - or at least third positions subject to the same measurement errors - as known in the field of differential GPS (dGPS). For example, the radio beacon 3 may have its own satellite navigation receiver (not shown), the reference positions P _{ref, i} the radio beacon 3 at about the same times, to which the positions P _{i are} created, measures and the OBU 10 makes available, for example, sent. With knowledge of the known position of a stationary radio beacon 3, the satellite navigation-determined positions P _i can then be related to the reference positions P _{ref, i} , which are subject to similar measurement errors, and thus measurement errors can be compensated, see path 29 in FIG Fig. 2 , In the same way, the positions P _i determined at similar times by neighboring OBUs 10 could also be used for the measurement error correction of the positions P _i generated by an OBU 10 of interest.

The invention is not limited to the illustrated embodiments, but includes all variants and modifications that fall within the scope of the appended claims.

Claims (15)

1. A method for identifying a vehicle (9) using a predetermined location (5 - 8), comprising:

   carrying, on the vehicle (9), an onboard unit (10) that via radio repeatedly broadcasts status messages (16), which each indicate a current relative distance (A_i) of the onboard unit (10) from the predetermined location (5 - 8) and a radio identifier (pID) that changes after each or several status messages (16);

   receiving at least one status message (16) in a radio beacon (3);

   detecting a location usage of the vehicle (9) by evaluating the at least one status message (16) based on the relative distance (A_i) indicated therein;

   transmitting an identification request (22) from the radio beacon (3) to that onboard unit (10) which is addressed by way of the radio identifier (pID) from the at least one status message;

   receiving and conducting a legitimacy check (24) of the identification request (22) in the onboard unit (10) and, if the request (22) is legitimate, transmitting (25) a unique identification (uID) of the onboard unit (10) to the radio beacon (3), the unique identification remaining the same over several changes of radio identifier.
2. The method according to claim 1, characterized in that information (P₀) about the predetermined location (5 - 8) is transmitted from the radio beacon (3) to the onboard unit (10), which based thereon and based on the current position (P_i) of the onboard unit calculates the relative distance (A_i).
3. The method according to claim 1, characterized in that information (P₀) about the predetermined location (5 - 8) is stored in the onboard unit (10), which based thereon and based on the current position (P_i) of the onboard unit calculates the relative distance (A_i).
4. The method according to any one of claims 1 to 3, characterized in that at least two status messages (16) are received in a radio beacon (3) and are associated with each other based on the radio identifiers (pID) indicated therein, and
   the location usage of the vehicle (9) is detected by evaluating the mutually associated status messages (16) based on the relative distances (A_i) indicated therein.
5. The method according to any one of claims 1 to 4, characterized in that the legitimacy check (24) is done by checking a cryptographic sender certificate (23) of the radio beacon (3) that is transmitted by the radio beacon (23) along with the identification request (22).
6. The method according to any one of claims 1 to 5, characterized in that the identification (uID) of the onboard unit (10) is transmitted to the radio beacon (3) via an encrypted channel (26).
7. The method according to any one of claims 1 to 6, characterized in that the identification (uID) received in the radio beacon (3) is recorded together with a time stamp (t) in a memory (28) so as to log the location usage, or is compared to at least one previously stored legitimate identification (uID_ref) so as to authorize the location usage, or is used to search for and debit a toll account associated with the identification (uID) so as to toll the location usage.
8. The method according to claim 7, characterized in that the radio beacon (3) transmits (27') a beacon identifier (bID) that is unique to the radio beacon to the onboard unit (10) after logging, authorization or tolling of the location usage, the onboard unit storing this identifier and transmitting the same at least along with a subsequent broadcast of the status message(s) (16) thereof or transmission of the identification (uID) thereof, and
   the radio beacon (3) ignores a status message (16) or identification (uID) received from an onboard unit (10) if the beacon identifier (bID) received along therewith is identical to its own beacon identifier (bID).
9. The method according to any one of claims 1 to 8, characterized in that the radio identifier (pID) is changed after every approximately 5 to 1000, preferably 20 to 100, status messages (16).
10. The method according to any one of claims 1 to 8, characterized in that the radio identifier (pID) is changed at the earliest after expiration of a predetermined time period.
11. The method according to any one of claims 1 to 8, characterized in that the radio identifier (pID) is kept the same while the onboard unit (10) is present in the radio coverage range (4) of one and the same radio beacon (3).
12. The method according to any one of claims 1 to 11, characterized in that each status message (16) also indicates the current position (P_i) and/or a current movement vector (M_i) of the onboard unit (10), which is or are also used during the detection of the location usage.
13. The method according to any one of claims 1 to 12, characterized in that the current position (P_i) of the onboard unit (10) is determined by way of satellite navigation (11) and improved by referencing to a reference position (29) of the radio beacon (3) that was determined by way of satellite navigation.
14. A radio beacon (3) for identifying a vehicle (9) using a predetermined location (5 - 8), the vehicle carrying an onboard unit (10) that via radio repeatedly broadcasts status messages (16), which each indicate a current relative distance (A_i) of the onboard unit (10) from the predetermined location (5 - 8) and a radio identifier (pID) that changes after each or several status messages (16), characterized by being configured to, with the aid of a processor (17) and a transceiver (18) connected thereto,
    receive at least one status message (16);
    detect a location usage by evaluating (20) the at least one status message (16) based on the relative distance (A_i) indicated therein;
    transmit an identification request (22) to that onboard unit (10) which is addressed by way of the radio identifier (pID) from the at least one status message (16); and then
    to receive a unique identification (uID) of the onboard unit (10) that remains the same over several radio identifier changes.
15. An onboard unit, comprising a processor (12), a satellite navigation receiver (11) for position determination, and a transceiver (13) for radio communication, wherein the onboard unit (10) is configured to, with the aid of the transceiver (13), repeatedly broadcast via radio status messages (16), which each contain a radio identifier (pID) of the onboard unit (10) that changes after several status changes (16), characterized by further being configured to indicate in each status message (16) the current relative distance (A_i) from a predetermined location (5 - 8), as determined by way of the satellite navigation receiver (11),
    receive, from a radio beacon (3), an identification request (22) that is addressed to the current radio identifier (pID) of the unit and contains a cryptographic sender certificate (23);
    validate the sender certificate (23); and if the same is valid,
    transmit (25) a unique identification (uID) of the onboard unit (10) to the radio beacon (3), the identification remaining the same over several changes of radio identifier.

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